1. Field of the Invention
This invention relates to an apparatus and method for mounting a circuit element on a substrate, and more particularly to an apparatus and method for a surface mounting-type electronic circuit element such as a Flat Plastic Package component (hereinafter referred to as "FPP"), a Plastic Leaded Chip Carrier component (hereinafter referred to as "PLCC"), a Leadless Chip Carrier component (hereafter referred to as "LCC"), a Small Outline Integrated Circuit component (hereinafter referred to as "SOIC") or thel ike on a substrate or a printed circuit board with high accuracy.
2. Description of the Prior Art
Such a conventional circuit element mounting apparatus is adapted to carry out positioning of a printed circuit board with respect to the apparatus by means of a positioning hole formed on a surface of the board. Also, positioning of a mounting head is carried out on the basis of origins of X and Y coordinates of an X-Y table head on which the mounting head is mounted. In the conventional mounting apparatus, a positional relationship between the positioning hole of the printed circuit board and a conducting pattern (wiring pattern) on the printed circuit board is deemed to be not varied depending on a printed circuit board and likewise a relative positional relationship between the positioning hole and the origins of the X and Y coordinates of the X-Y table head is deemed to be constant irrespective of a printed circuit board.
The positioning hole of the printed circuit board is formed by drilling subsequently to formation of the conducting pattern, resulting in a positional error in the formation of the hole being as large as about 0.3 mm. This causes misregistration as large as 0.3 mm to occur between the amount of movement of the mounting head to a circuit element mounting position on the printed circuit board and the actual circuit element mounting position. Unfortunately, the relative positional relationship between the positioning hole and the origin as of the X-Y table which is merely kept constant in the conventional apparatus fails to prevent the misregistration. The misregistration of about 0.3 mm often causes a failure in connecting of a surface mounting-type circuit element called an FPP, a PLCC, an LCC or an SOIC with respect to a substrate, because it is so constructed that an interval between lead wires of the circuit element is small.
Also, the deviation of the positioning hole on the printed circuit board causes mounting of a circuit element on the printed circuit board to be carried out at a wrong posture.